let n be Nat; for T being TopSpace
for A being closed Subset of T st T is normal holds
for X being Subset of (TOP-REAL n) st X is compact & not X is boundary & X is convex holds
for f being Function of (T | A),((TOP-REAL n) | X) st f is continuous holds
ex g being Function of T,((TOP-REAL n) | X) st
( g is continuous & g | A = f )
set TR = TOP-REAL n;
let T be TopSpace; for A being closed Subset of T st T is normal holds
for X being Subset of (TOP-REAL n) st X is compact & not X is boundary & X is convex holds
for f being Function of (T | A),((TOP-REAL n) | X) st f is continuous holds
ex g being Function of T,((TOP-REAL n) | X) st
( g is continuous & g | A = f )
let A be closed Subset of T; ( T is normal implies for X being Subset of (TOP-REAL n) st X is compact & not X is boundary & X is convex holds
for f being Function of (T | A),((TOP-REAL n) | X) st f is continuous holds
ex g being Function of T,((TOP-REAL n) | X) st
( g is continuous & g | A = f ) )
assume A1:
T is normal
; for X being Subset of (TOP-REAL n) st X is compact & not X is boundary & X is convex holds
for f being Function of (T | A),((TOP-REAL n) | X) st f is continuous holds
ex g being Function of T,((TOP-REAL n) | X) st
( g is continuous & g | A = f )
let S be Subset of (TOP-REAL n); ( S is compact & not S is boundary & S is convex implies for f being Function of (T | A),((TOP-REAL n) | S) st f is continuous holds
ex g being Function of T,((TOP-REAL n) | S) st
( g is continuous & g | A = f ) )
assume A2:
( S is compact & not S is boundary & S is convex )
; for f being Function of (T | A),((TOP-REAL n) | S) st f is continuous holds
ex g being Function of T,((TOP-REAL n) | S) st
( g is continuous & g | A = f )
let f be Function of (T | A),((TOP-REAL n) | S); ( f is continuous implies ex g being Function of T,((TOP-REAL n) | S) st
( g is continuous & g | A = f ) )
assume A3:
f is continuous
; ex g being Function of T,((TOP-REAL n) | S) st
( g is continuous & g | A = f )
A4:
[#] (T | A) = A
by PRE_TOPC:def 5;
A5:
[#] ((TOP-REAL n) | S) = S
by PRE_TOPC:def 5;
per cases
( A is empty or not A is empty )
;
suppose A8:
not
A is
empty
;
ex g being Function of T,((TOP-REAL n) | S) st
( g is continuous & g | A = f )set H =
ClosedHypercube (
(0. (TOP-REAL n)),
(n |-> 1));
consider h being
Function of
((TOP-REAL n) | S),
((TOP-REAL n) | (ClosedHypercube ((0. (TOP-REAL n)),(n |-> 1)))) such that A9:
h is
being_homeomorphism
and
h .: (Fr S) = Fr (ClosedHypercube ((0. (TOP-REAL n)),(n |-> 1)))
by BROUWER2:7, A2;
A10:
rng h = [#] ((TOP-REAL n) | (ClosedHypercube ((0. (TOP-REAL n)),(n |-> 1))))
by A9, TOPS_2:def 5;
A11:
not
(TOP-REAL n) | S is
empty
by A5, A2;
then reconsider hf =
h * f as
Function of
(T | A),
((TOP-REAL n) | (ClosedHypercube ((0. (TOP-REAL n)),(n |-> 1)))) ;
consider g being
Function of
T,
((TOP-REAL n) | (ClosedHypercube ((0. (TOP-REAL n)),(n |-> 1)))) such that A12:
g is
continuous
and A13:
g | A = hf
by A3, A9, A4, A8, A11, A1, Th22;
reconsider hg =
(h ") * g as
Function of
T,
((TOP-REAL n) | S) ;
take
hg
;
( hg is continuous & hg | A = f )
h " is
being_homeomorphism
by A9, TOPS_2:56;
hence
hg is
continuous
by A12, TOPS_2:46;
hg | A = fA14:
rng f c= the
carrier of
((TOP-REAL n) | S)
;
A15:
dom h = [#] ((TOP-REAL n) | S)
by A9, TOPS_2:def 5;
thus hg | A =
(h ") * hf
by RELAT_1:83, A13
.=
((h ") * h) * f
by RELAT_1:36
.=
(id ([#] ((TOP-REAL n) | S))) * f
by A9, A10, A15, TOPS_2:52
.=
f
by A14, RELAT_1:53
;
verum end; end;